This application relates to a gas pin valve for a gas cylinder and specifically to a gas pin valve for a gas cylinder including tamper resistance and tamper evident features.
Typically, a gas cylinder is filled with a liquid or gas under a desired pressure. The gas cylinder is designed to withstand specific pressures and to deliver the gas and liquid at pressure to specific devices. Commonly, devices such as paintball guns or fire extinguishers use the pressurized gas within the cylinder to propel a paintball in the case of the paintball gun, or a fire suppression chemical in the case of a fire extinguisher. In any device, it is desired to maintain the gas or liquid within the cylinder at a given pressure until use. It is known to use a pin-type valve threaded into the outlet of the gas cylinder to control the outlet of gas pressure from the cylinder.
Typically, a pin valve includes a piston held against a seal by a spring. The spring is trapped between the piston and a threaded screw and provides a sufficient force within the gas cylinder to prevent unwanted expulsion of gas from the gas cylinder. Typically, gas pressure within the cylinder acts in concert with the spring to bias the piston against the seal. Gas is only expelled from the gas cylinder by overcoming the force of the spring and pressure exerted by gas within the cylinder.
The pin valve is threaded into the outlet of the gas cylinder and includes a threaded member having an inlet hole. When it is desired to release pressure from the cylinder, a pin extending from the piston through the opening is pushed downward. By pushing downward on the pin, the piston is lifted off the seal and gas pressure is allowed to escape through the inlet. The pin portion of the piston extends through the opening and is of a diameter smaller than the opening to allow gas pressure to be released from the gas cylinder.
As is appreciated, the spring force exerted by the spring onto the piston contributes a substantial portion of the biasing force used to maintain gas within the cylinder. The spring force exerted against the piston is determined by a distance between a rear end of the piston and a threaded member threaded into the body of the pin valve. Currently, the threaded member is machined with outer threads that are mated to internal threads that are fabricated within the body of the pin valve. The threaded member is then machined with an allen-type tool interface for assembly within the pin valve body against the force of the spring. As appreciated, machining of internal and external threads require expensive and time consuming machining operations. Further, such pin valves are commonly assembled to gas cylinders used in recreational devices where cost is a great factor determining commercial success. As appreciated, it is always desirable to decrease the cost of producing consumer goods.
Further, in some applications it is desirable to inhibit or evidence tampering of preset conditions. As appreciated, the preset spring force of the pin valve determines the amount of and point at which gas is exhausted from the gas cylinder. In some instances, tampering with this pin valve and the point and pressure required to release gas from within the gas cylinder can cause harm or injury. In such instances, it is desirable to evidence tampering by an operator in order to limit liability. Further, it is also desirable to prevent tampering by designing a mechanism that is destroyed upon modification and rendered unusable.
Accordingly, it is desirable to develop and design a pin valve that reduces production costs while also preventing and evidencing tampering.